Zoom lens and camera with zoom lens

ABSTRACT

A zoom lens of variable power ratio of the order of 3 in which the whole of the zoom lens is made up of three lens elements groups and the power configuration of each of the groups has an arrangement of negative, positive, and negative. The zoom lens includes, sequentially from an object side thereof, a first lens elements group which has a negative refraction power as a whole, a second lens elements group which has a positive refraction power as a whole, and a third lens element group, which has a negative refraction power as a whole. A variable power is realized by shifting the positions of the first and second lens elements group in the direction of an optical axis thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S. applicationSer. No. 11/701,899 filed Feb. 2, 2007, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a high-performance and fast (small ƒnumber) zoom lens which is used for a small sized photographic apparatuswhich utilizes an image sensor such as a CCD (charged coupled device)which is designed to be installed mainly on a digital still camera.

Small sized digital still cameras have been produced by devising systemsand mechanisms which include the adoption of a single focus lens whichcan help reduce a dimension of the camera in a direction of an opticalaxis of the lens as much as possible in order to design a thin cameramain body and, furthermore, the creation of a lens such as one disclosedin, for example, the Japanese Patent Unexamined Publication No.2002-228922 (Patent Document No. 1) in which telecentric characteristicswhich are inherent in image sensors such as CCD's are taken intoconsideration. However, the installation of zoom lenses on cameras hasbeen in strong demand, and currently, even in the field of digital stillcameras, a main stream of digital still cameras produced and sold hasbeen shifted to those with a zoom lens.

The invention is such as to provide a small sized zoom lens or a smallcamera with a zoom lens.

SUMMARY OF THE INVENTION

According to a preferred aspect of the invention, there is provided azoom lens including, sequentially from an object side thereof, a firstlens elements group having a negative refraction power as a whole, asecond lens elements group having a positive refraction power as a wholeand a third lens element group having a negative refraction power as awhole. The first lens elements group is made up by disposing three lenselements which include a first lens element which is a negative ordiverging lens, a second lens element which is a positive or converginglens, and a third lens element which is a negative or diverging lens.The second lens elements group is made up by disposing four lenselements which include a fourth lens element which is a positive orconverging lens, a fifth lens element which is a positive or converginglens, a sixth lens element which is a negative or diverging lens, and aseventh lens element which is a positive or converging lens. And thethird lens element group is made up by disposing an eighth lens elementwhich is a negative or diverging lens. A variable power is realized byshifting the positions of the first lens elements group and the secondlens elements group in a direction of an optical axis thereof, or byshifting, in addition to the positions of the first lens elements groupand the second lens elements group, the position of the third lenselement group in a direction of an optical axis thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of lens elements of afirst embodiment of a zoom lens of the invention.

FIG. 2 is a diagram showing aberrations of the first embodiment.

FIG. 3 is a diagram showing the configuration of lens elements of asecond embodiment of a zoom lens of the invention.

FIG. 4 is a diagram showing aberrations of the second embodiment.

FIG. 5 is a diagram showing the configuration of lens elements of athird embodiment of a zoom lens of the invention.

FIG. 6 is a diagram showing aberrations of the third embodiment.

FIG. 7 is a diagram showing the configuration of lens elements of afourth embodiment of a zoom lens of the invention.

FIG. 8 is a diagram showing aberrations of the fourth embodiment.

FIG. 9 is a diagram showing the configuration of lens elements of afifth embodiment of a zoom lens of the invention.

FIG. 10 is a diagram showing aberrations of the fifth embodiment.

FIG. 11 is a diagram showing the configuration of lens elements of asixth embodiment of a zoom lens of the invention.

FIG. 12 is a diagram showing aberrations of the sixth embodiment.

FIG. 13 is a diagram showing the configuration of lens elements of aseventh embodiment of a zoom lens of the invention.

FIG. 14 is a diagram showing aberrations of the seventh embodiment.

FIG. 15 is a diagram showing the configuration of lens elements of aneighth embodiment of a zoom lens of the invention.

FIG. 16 is a diagram showing aberrations of the eighth embodiment.

FIG. 17 is a diagram showing the configuration of lens elements of aninth embodiment of a zoom lens of the invention.

FIG. 18 is a diagram showing aberrations of the ninth embodiment.

FIG. 19 is a diagram showing the configuration of lens elements of atenth embodiment of a zoom lens of the invention.

FIG. 20 is a diagram showing aberrations of the tenth embodiment.

FIG. 21 is a diagram showing the configuration of lens elements of an11th embodiment of a zoom lens of the invention.

FIG. 22 is a diagram showing aberrations of the 11th embodiment.

FIG. 23 is a diagram showing the configuration of lens elements of a12th embodiment of a zoom lens of the invention.

FIG. 24 is a diagram showing aberrations of the 12th embodiment.

FIG. 25 is a diagram showing the configuration of lens elements of a13th embodiment of a zoom lens of the invention.

FIG. 26 is a diagram showing aberrations of the 13th embodiment.

FIG. 27 is a diagram showing the configuration of lens elements of a14th embodiment of a zoom lens of the invention.

FIG. 28 is a diagram showing aberrations of the 14th embodiment.

FIG. 29 is a diagram showing the configuration of lens elements of a15th embodiment of a zoom lens of the invention.

FIG. 30 is a diagram showing aberrations of the 15th embodiment.

FIG. 31 is a diagram showing the configuration of lens elements of a16th embodiment of a zoom lens of the invention.

FIG. 32 is a diagram showing aberrations of the 16th embodiment.

FIG. 33 is a diagram showing the configuration of lens elements of a17th embodiment of a zoom lens of the invention.

FIG. 34 is a diagram showing aberrations of the 17th embodiment.

FIG. 35 is a diagram showing the configuration of lens elements of an18th embodiment of a zoom lens of the invention.

FIG. 36 is a diagram showing aberrations of the 18th embodiment.

FIG. 37 is a diagram showing the configuration of lens elements of a19th embodiment of a zoom lens of the invention.

FIG. 38 is a diagram showing aberrations of the 19th embodiment.

FIG. 39 is a diagram showing the configuration of lens elements of a20th embodiment of a zoom lens of the invention.

FIG. 40 is a diagram showing aberrations of the 20th embodiment.

FIG. 41 is a diagram showing the configuration of lens elements of a21st embodiment of a zoom lens of the invention.

FIG. 42 is a diagram showing aberrations of the 21st embodiment.

FIG. 43 is a diagram showing the configuration of lens elements of a22nd embodiment of a zoom lens of the invention.

FIG. 44 is a diagram showing aberrations of the 22nd embodiment.

FIG. 45 is a diagram showing the configuration of lens elements of a23rd embodiment of a zoom lens of the invention.

FIG. 46 is a diagram showing aberrations of the 23^(rd) embodiment.

FIG. 47 is a diagram showing the configuration of lens elements of a24th embodiment of a zoom lens of the invention.

FIG. 48 is a diagram showing aberrations of the 24th embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, Embodiments 1 to 16 of the invention will be described byreference to specific numerical examples thereof.

In Embodiments 1 to 16 which will be described below, a zoom lens ismade up of, sequentially from an object side thereof, a first lenselements group LG1, a second lens elements group LG2 and a third lenselements group LG3.

The first lens elements group LG1 has a negative refraction power as awhole and is made up by disposing a first lens element L1 (an objectside surface of the first lens element L1 is to be referred to as a1^(st) surface, and an image side surface as a 2^(nd) surface) which isa lens having a negative refraction power (hereinafter referred to as anegative lens), a second lens element L2 (an object side surface of thesecond lens element L2 is to be referred to as a 3^(rd) surface, and animage side surface as a 4^(th) surface) which is a lens having apositive refraction power (hereinafter, referred to as a positive lens)and a third lens element L3 (an object side surface of the third lenselement L3 is to be referred to as a 5^(th) surface, and an image sidesurface as a 6^(th) surface) which is a negative lens.

The second lens elements group LG2 has a positive refraction power as awhole and is made up by disposing a fourth lens element L4 (an objectside surface of the fourth lens element L4 is to be referred to as a7^(th) surface, and an image side surface as an 8^(th) surface) which isa positive lens, a fifth lens element L5 (an object side surface of thefifth lens element L5 is to be referred to as a 9^(th) surface, and animage side surface as a 10^(th) surface) which is a positive lens, asixth lens element L6 (although an object side surface of the sixth lenselement L6 is referred to be as an 11^(th) surface and an image sidesurface as a 12^(th) surface, in a case where the fifth lens element L5and the sixth lens element L6 are cemented together, only the surfacenumber of the 11^(th) surface is indicated as parenthesized, or in acase where the 11^(th) surface or the 12^(th) surface constitutes aresin surface of a compound aspheric lens, a boundary plane between theresin and air is to be referred to as an HB plane) which is a negativelens and a seventh lens element L7 (an object side surface of theseventh lens element L7 is to be referred to as a 13^(th) surface, andan image side surface as a 14^(th) surface) which is a positive lens.

The third lens element group LG3 has a negative refraction power as awhole and is made up by disposing an eighth lens element L8 (an objectside surface of the eighth lens element L8 is to be referred to as a15^(th) surface, and an image side surface as a 16^(th) surface) whichis a negative lens.

In addition, a crystal optical filter LPF (an object side surface of thecrystal optical filter LPF is to be referred to as a 17^(th) surface,and an image side surface as an 18^(th) surface) and a cover glass CG(an object side surface of the cover glass CG is to be referred to as a₁₉ ^(th) surface, and an image side surface as a 20^(th) surface) whichis for protection of a photographic portion of a CCD are disposed withinan air space defined between the image side surface, which is the ₁₆^(th) surface, of the eighth lens element L8 and an image plane.

The cutting of infrared rays which is required in handling an imagesensor such as a CCD is understood to be implemented by applying aninfrared reflection coating on to one side of refracting surfaces of thecrystal optical filter LPF and, hence, is not illustrated.

A variable power is realized by shifting the positions of the first lenselements group LG1 and the second lens elements group LG2 in a directionof an optical axis of the zoom lens, or shifting, in addition to thefirst lens elements group LG1 and the second lens elements group LG2,the position of the third lens element group LG3.

In addition, in each embodiment, although a focal point adjustment foran object at a finite distance can be realized by shifting the positionof the first lens elements group LG1 or the third lens element group LG3in the direction of the optical axis, the implementation of focal pointadjustment is not limited to the relevant method.

Furthermore, the shape of an aspheric surface used in each embodiment isdefined as is known by giving a paraxial radius of curvature: R, a conicconstant: K and high-order aspherical coefficients: A, B, C, D on acurved surface that is obtained by rotating round the optical axis acurve given by an aspherical equation:

Z=(Y ² /R)/[1+√{1−(1+K)(Y/R)² }]+A·Y ⁴ +B·Y ⁶ +C·Y ⁸ +C·Y ¹⁰+. . .

when the Z axis is taken in the direction of the optical axis and the Yaxis is taken in a direction which intersects the optical axis at rightangles. Note that in the description of conic constants and high-orderaspherical coefficients in tables, “E and numerals which follow it”represents an “exponent of 10.” For example, “E-04” means 10⁻⁴, and anumber just before it is multiplied by this number.

In addition, this embodiment satisfies the following conditionalexpression (1) with respect to the power that the first lens elementgroup possesses, the following conditional expression (2) with respectto the size of the whole lens system, and the following conditionalexpression (3) with respect to the power that the third lens elementgroup possesses.

−0.8≦f _(w) /f _(I)≦−0.45   (1)

4.5≦TL _(w) /f _(w)≦7.5   (2)

−0.55≦f _(w) /f _(III)≦0   (3)

where,

f_(w): composite focal length of the whole lens system at wide-angle end

f_(I): composite focal length of the first lens element group

f_(III): composite focal length of the third lens element group

TL_(w): distance from an object side surface of the first lens elementmaking up the first lens elements group to the image plane at wide-angleend (where, a parallel plane glass portion is converted into an airspace distance).

The conditional expression (1) relates to a proper distribution of powerto the first lens element group which has the negative power.

This constitutes a balance for a condition for proper correction of thesize and aberrations of the whole optical system. In the event that alower limit is surpassed, this means that the negative power of thefirst lens elements group is large, and in conjunction with this, thepositive power of the second lens elements group has to be intensified,and it becomes difficult to keep a balance among the aberrations,whereby the performance is decreased. In contrast to this, in the eventthat an upper limit is surpassed, large air spaces to the second lenselements group having the positive power have to be taken, whereby thesize of the whole optical system is enlarged, and as a result, thecompactness is lost.

The conditional expression (2) is such as to control the overall lengthof the zoom lens at the wide-angle end. Namely, this constitutes acondition which becomes a measure of reduction in size of the zoom lensof the invention.

In the event that an upper limit is surpassed, although it becomesadvantageous in correcting the aberrations, it becomes impossible toprovide a compact zoom lens, which is the object of the invention. Onthe contrary, in the event that a lower limit is surpassed, the power ofeach lens element has to be increased, and this calls for deteriorationin the aberrations, whereby the production of the object zoom lensbecomes difficult in reality.

The third conditional expression (3) is a conditional expression whichis related to the power that the third lens element group possesses. Itis a prime characteristic that it remains within the negative range,whereby a function is provided to cause the exit pupil of the opticalsystem to approach the image plane side.

In general, the fact that the exit pupil is positioned in the proximityof the image plane is advantageous in making the zoom lens compact insuch a way as to decrease the overall length thereof. In contrastthereto, this means that the telecentric characteristics on theperiphery of the picture plane are collapsed. Namely, a principal ray oflight passing through an image point on the periphery of the pictureplane is angled, which is not good for an optical system which uses animage sensor such as a CCD.

Normally, in a zoom lens at a magnification of the order of 3×, theangle of a principal ray of light passing through an image point on theperiphery of the picture plane is changed by an operation for variablepower. Although it is natural that the amount of change differsdepending on designs, in many cases, the amount of change in angle isnearly on the order of 10° or more at an image point of a maximum imageheight (for example, 10° at the wide-angle end, 0° at the telephotoend). In the case of a single focus lens which is free from change inangle of the principal ray of light, however, the change can exceed 20°by adapting the construction of a microlens of a CCD.

With the zoom lens of this embodiment, since by giving the negativepower to the third lens element group, the change in angle of theprincipal ray of light when changing the magnification becomes about1.9° to 4.9°, which is extremely small compared to the correspondingamount of change of a zoom lens of normal type, a large angle can betaken for the principal ray of light. In embodiments which will bedescribed later on, the angle of a principal ray of light (when abisector of an angle formed by an upper ray of light and a lower ray oflight is defined as a principal ray of light) at a maximum image pointon the picture plane is limited to be a maximum of 20°, and a lowerlimit value that is specified by the conditional expression of theconditional expression (3) is to be a range where the negative power ofthe third lens element group can be taken in that state. When the lowerlimit is surpassed, although it is effective in making the systemcompact, the angle of the principal ray of light exceeds 20°, andproblems are caused of shading and insufficient quantity of light,whereby the high image quality required for a digital still camera orthe like becomes unable to be maintained. On the contrary, when an upperlimit is surpassed, it means that an optical system of a size resultswhich does not have to be made compact by the application of theinvention.

Furthermore, this embodiment satisfies the following conditionalexpression (4) with respect to the power that the second lens element ofthe first lens elements group possesses, the following conditionalexpression (5) with respect to the dispersion properties that aredistributed to each lens element of the first lens elements group, andthe following conditional expression (6) with respect to the refractiveindex of the second lens element.

0.22≦f _(w) /f ₂≦−0.55   (4)

15≦(ν₁+ν₃)/2−ν₂   (5)

1.65≦n₂   (6)

where,

f₂: focal length of the second lens element which makes up the firstlens elements group

ν₁: Abbe number of the first lens element which makes up the first lenselements group

ν₂: Abbe number of the second lens element which makes up the first lenselements group

ν₃: Abbe number of the third lens element which makes up the first lenselements group

n₂: refractive index relative to the d line of the second lens elementwhich makes up the first lens elements group.

The conditional expression (4) specifies a requirement for correctingproperly basic aberrations of the first lens elements group as a whole.

Namely, as has been described above, although the first lens elementsgroup is made up of the negative, positive and negative powers,chromatic aberration and curvature of field can basically be correctedby imparting a proper positive power to the second lens element within arange specified by the conditional expression (4) along with theselection of glass material based on the conditional expression (5) andthe conditional expression (6). In the event that an upper limit issurpassed, although the power of the positive lens becomes too large,the power of the negative lens inevitably becomes too large, andhigh-order aberrations are produced. In the event that a lower limit issurpassed, although a combination of small powers is enabled, thecorrection effect of chromatic aberration and curvature of field issmall, and in this case, too, a proper correction of the aberrationsbecomes impossible.

The conditional expression (5) relates to the distribution of Abbenumbers of the negative lenses and the positive lens which make up thefirst lens elements group. This is a conditional expression for properlymaintaining the chromatic aberration correction for the first lenselements group, and a proper distribution of powers can be realized toenable a proper correction of chromatic aberration by implementing theselection of glass materials for the negative lenses and the positivelens which make up the first lens elements group based on a conditionspecified under the conditional expression (5). In the event that alower limit is surpassed, the power of each lens becomes excessive inorder to correct chromatic aberration, and the aberrations aredeteriorated.

The conditional expression (6) specifies a condition for correction ofcurvature of field. The reduction in the Petzval sum is deal with byincreasing the refractive index of the second lens element which is theonly positive lens in the first lens element group, and therefore, inthe event that a lower limit is surpassed, the curvature of field isincreased.

In addition, in this embodiment, the first lens element which makes upthe first lens elements group is an aspherical lens, and the embodimentsatisfies the following conditional expression (7) with respect to theconfiguration of an image side surface thereof and also satisfies thefollowing conditional expression (8) with respect to a relativecharacteristic on configuration between the image side surface of thefirst lens element and an object side surface of the second lens elementwhich makes up the first lens elements group.

0.4≦f _(w) /r ₂≦1.4   (7)

0≦r ₂ /r ₃≦1.5   (8)

where,

r₂: radius of curvature of the image side surface of the first lenselement which makes up the first lens elements group

r₃: radius of curvature of the object side surface of the second lenselement which makes up the first lens elements group.

A basic configuration for suppressing the occurrence of off-axisaberrations such as coma aberration and distortion is realized byproviding a concentric configuration relative to the entrance pupilunder the strong negative power which is imparted to the first lenselement, and the conditional expression (7) specifies a condition forrealizing the relevant configuration.

Namely, the first lens element is formed into a meniscus configurationhaving the strong negative power. In the event that with the object sidesurface of the first lens element formed into an aspherical shape, areduction in the overall length is implemented strongly, although theoverall configuration can be said to take a meniscus configuration, whenlooking at a paraxial radius of curvature, there may occur a case wherea resulting configuration constitutes a double-concave lens. In theevent that a lower limit of the conditional expression (7) is surpassed,the occurrence of coma aberration and distortion cannot be suppressedsufficiently. On the contrary, in the event that an upper limit issurpassed, although it is effective to suppress the occurrence ofaberrations, the curvature of the shape of the meniscus negative lensbecomes excessive, and the production of the lens becomes difficult.

In addition, in order to correct effectively off-axis aberrations suchas astigmatism and distortion, it is better to form the image sidesurface of the first lens element into an aspherical surface shape, andas this occurs, although as aspherical surfaces to be manufactured, aglass molded aspherical surface, a composite aspherical surface with aresin material and the like are preferred, there is no specificlimitation on the method for manufacturing the aspherical surface.

The conditional expression (8) is a conditional expression forcorrecting properly a positive spherical aberration that is caused by astrong diverging action occurring on the image side surface of the firstlens element having the negative power. In the event that an upper limitis surpassed, a negative spherical aberration by the second lens elementbecomes excessive, and on the contrary, in the event that a lower limitis surpassed, the positive spherical aberration by the first lenselement becomes excessive, whereby in either of the cases, the sphericalaberrations cannot be corrected properly.

In addition, this embodiment satisfies the following conditionalexpression (9) with respect to a positive composite power that thefourth lens element and the fifth lens element of the second lenselements group possess, the following conditional expression (10) withrespect to the negative power that the sixth lens element possesses, thefollowing conditional expression (11) with respect to the dispersionproperties that are distributed to the fourth lens element, the fifthlens element and the sixth lens element which are disposed closer to theobject side in the second lens elements group, and the followingconditional expression (12) with respect to the refractive index thateach of the similar lens elements possesses.

0.5≦f _(w) /f _(4,5)≦1.5   (9)

−1.5≦f _(w) /f ₆≦−0.25   (10)

28≦(ν₄+ν₅)/2−ν₆  (11)

(n ₄ +n ₅)/2−n ₆≦−0.24   (12)

where,

f_(4, 5): composite focal length of the fourth lens element and thefifth lens element which make up the second lens elements group

f₆: focal length of the sixth lens element which makes up the secondlens elements group

(where, in the event that the sixth lens element makes up a compositeaspherical lens, a composite focal length of a base spherical lens and aresin portion)

ν₄: Abbe number of the fourth lens element which makes up the secondlens elements group

ν₅: Abbe number of the fifth lens element which makes up the second lenselements group

ν₆: Abbe number of the sixth lens element which makes up the second lenselements group

(where, Abbe number of a glass material of a base spherical lens, in theevent that the sixth lens element makes up a composite aspherical lens)

n₄: refractive index relative to the d line of the fourth lens elementwhich makes up the second lens elements group

n₅: refractive index relative to the d line of the fifth lens elementwhich makes up the second lens elements group

n₆: refractive index relative to the d line of the sixth lens elementwhich makes up the second lens elements group.

The conditional expression (9) relates to the fourth lens element andthe fifth lens element which are disposed closest to the object side inthe second lens elements group and which have the strong positive power.

The conditional expression (9) provides a condition for imparting alarge positive power for collecting rays of light which diverge from thefirst lens elements group and correcting properly the aberrations. Inthe event that an upper limit is surpassed, the positive power becomesexcessive, and at the same time, the spherical aberration is correctedinsufficiently, whereas in the event that a lower limit is surpassed,the positive power for collecting light rays from the first lenselements group becomes insufficient, and an excessive correction ofspherical aberration results. In either of the cases, however, inaddition to spherical aberration, the off-axis aberration such as comaaberration and chromatic aberration are largely affected.

The conditional expression (10) relates to the negative power of thenegative lens which makes up the second lens elements group andspecifies a prime requirement for correction of the basic chromaticaberration and curvature of field of the second lens elements group as awhole.

Namely, in the event that an upper limit is surpassed, although a lensconfiguration made up of a combination in which the powers of therespective lens elements of the second lens elements group are small,the correction of chromatic aberration and curvature of field becomesinsufficient, and on the contrary, in the event a lower limit issurpassed, since each lens power becomes excessive, high-order sphericalaberration and coma aberration are produced, and a good performancecannot be obtained.

The conditional expression (11) relates to the distribution of Abbenumbers of the positive lens and the negative lens which are disposed onthe object side in the second lens elements group so as to be used in aportion which keeps a balance of aberrations while having a strongpositive power for collecting rays of light which diverge from the firstlens elements group. In this case, although the seventh lens elements,which also makes up the second lens elements group, has a relativelylarge positive power, the magnitude of the power is such as to bedetermined in many cases by a balance with the negative power of thethird lens element group, and therefore, the seventh lens element is notrepresented in the conditional expression (11). Consequently, theconditional expression (11) is expressed by the fourth lens elements andfifth lens element which are positive lenses and the sixth lens elementwhich is a negative lens and specifies a condition for keeping a balancewith the aberrations while correcting properly the chromatic aberrationof the whole lens system. In the event that a lower limit is surpassed,the power of each lens element has to be increased so as to correctchromatic aberration, which constitutes a disadvantageous condition forcorrecting spherical aberration and coma aberration.

The conditional expression (12) relates to the correction of curvatureof field in the second lens elements group. In order to balance anegative Petzval sum produced from the first lens elements group, therefractive index of each lens element needs to be a value which fallswithin a range specified by a condition presented by the relevantexpression. In the event that an upper limit is surpassed, the Petzvalsum becomes too small, and the correction of curvature of field becomesexcessive.

In addition, in this embodiment, of refracting surfaces of each lenselement which makes up the second lens elements group, at least one ofthe refracting surfaces is formed into an aspherical shape, and theembodiment satisfies the following conditional expression (13) withrespect to the configuration of an object side surface of the fourthlens element and the following conditional expression (14) with respectto an image side surface of the sixth lens element.

0.2≦f _(w) /r ₇≦1.0   (13)

0.4≦f _(w) /r ₁₂≦1.6   (14)

where,

-   r₇: radius of curvature of the object side surface of the fourth    lens element which makes up the second lens elements group-   r₁₂: radius of curvature of the image side surface of the sixth lens    element which makes up the second lens elements group

(where, radius of curvature of a boundary plane between resin and air inthe event that the image side surface of the sixth lens element is madeup of a resin lens surface of a compound lens).

The conditional expression (13) is a conditional expression in relationto the configuration of the object side surface of the fourth lenselement. Since the object side surface of the fourth lens element isdisposed right behind an aperture stop, the relevant surface plays animportant role in correcting spherical aberration. The conditionalexpression (13) specifies a condition for properly correcting sphericalaberration in connection with the negative power of the first lenselements group.

In the event that an upper limit of the conditional expression (13) issurpassed, although off-axis aberrations such as coma aberration andastigmatism get easy to be corrected, an insufficient correction ofspherical aberration results. On the contrary, in the event that a lowerlimit is surpassed, an excessive correction of spherical aberrationresults, and at the same time, a proper correction of the off-axisaberrations becomes difficult.

The conditional expression (14) is a conditional expression whichrelates to the configuration of the image side surface of the sixth lenselement. The object side surface of the fourth lens element that isexpressed in the previous conditional expression (13) is a surface whichis disposed closest to an incident side in the second lens elementsgroup, and moderate negative spherical aberration and coma aberrationthat are produced on the relevant surface are corrected by producing apositive aberration on the image side surface of the sixth lens element.Consequently, in the event that an upper limit is surpassed, thepositive spherical aberration becomes excessive, and on the contrary, inthe event that a lower limit is surpassed, the negative sphericalaberration becomes excessive, whereby in either of the cases, a propercorrection of spherical aberration and coma aberration is disabled.

Furthermore, in this embodiment, the third lens element group is made upof only the eighth lens element which is the negative lens, and theembodiment satisfies the following conditional expression (15) withrespect to the configuration of the object side surface of the eighthlens element.

−2.0≦f _(w) /r ₅≦0.2   (15)

where,

r₁₅: radius of curvature of the object side surface of the eighth lenswhich makes up the third lens element group.

As is shown by the conditional expression (15), in order to cause raysof light converging from the second lens elements group to focus on animage plane with production of little aberration, basically, theconfiguration of the object side surface of the eighth lens element ispreferably formed into a concentric shape relative to the second lenselements group.

Consequently, although it is good that the value of the conditionalexpression (15) basically takes a negative value, depending on designspecifications such as overall length, in the event that the relevantsurface is an aspherical surface, as is shown at an upper limit of theconditional expression (15), there may occur a case where the expressiontakes a slightly positive value. However, in the event that the valuesurpasses an upper limit to become too large, both the peripheral shapeand the concentric shape are changed, whereby aberrations such as commaaberration and distortion are produced. In the event that a lower limitis surpassed, the Petzval sum due to the object side surface of theeighth lens element becomes too large on the negative side, and theangle of an emerging ray of light also becomes excessive.

EMBODIMENT 1

A numerical example for a first embodiment of a zoom lens of theinvention will be shown in Table 1. In addition, FIG. 1 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 2is a diagram showing aberrations thereof. In the table and figures, fdenotes the focal length of a whole lens system (hereinafter, valuesshown therein are from the left-hand side values at a wide-angle end,intermediate area and telephoto end), F_(no) ƒ number, and 2ω totalangle of view of lens. In addition, R denotes radius of curvature, Dlens element thickness or lens element space, N_(d) refractive index ofd line, and ν_(d) Abbe number of d line. In diagrams showingaberrations, d, g, C in diagrams showing spherical aberrations denoteaberration curves in individual wavelengths. In addition, S.C. denotessine condition. In astigmatism diagrams, S denotes sagital, and Mdenotes meridional.

TABLE 1 f = 6.84~11.56~19.50 F = 1.96~2.66~3.74 2 ω = 69.23~43.08~26.17Surface number R D N_(d) ν_(d) 1 19.150 0.72 1.80610 40.73 2 6.645 3.07— — 3 10.387 1.67 1.84666 23.78 4 24.486 1.83 — — 5 −10.585 0.60 1.6324663.80 6 −96.268 13.56~6.08~1.15  — — 7 14.518 1.57 1.63246 63.80 8−49.735 0.10 — — 9 5.882 2.25 1.49700 81.61 10 52.012 1.76 — — 11214.910 0.40 2.13120 24.07 12 7.481 0.19 1.51576 52.63 HB 10.449 2.24 —— 13 16.417 1.70 1.62588 35.74 11 −12.343 5.63~6.35~9.82 — — 15 −6.3960.82 1.52470 0.00 16 −10.024 0.57~3.85~6.50 — — 17 ∞ 0.64 1.54892 69.7618 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 9.19296E−04 B = −4.56716E−05 C =1.31412E−06 D = −1.73534E−08 E = 9.03438E−11 2^(nd) surface K =0.00000E+00 A = 8.11291E−04 B = −3.72117E−05 C = −2.90672E−07 D =5.16007E−08 E = −8.31094E−10 HB plane K = 0.00000E+00 A = 1.68001E−03 B= 1.68591E−05 C = 1.09717E−06 15^(th) surface K = 0.00000E+00 A =1.95798E−04 B = 4.34601E−05 C = −5.07535E−06 D = 3.28041E−07 E =−7.45431E−09

EMBODIMENT 2

A numerical example for a second embodiment of a zoom lens of theinvention will be shown in Table 2. In addition, FIG. 3 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 4is a diagram showing aberrations thereof.

TABLE 2 f = 7.44~12.58~21.20 F = 2.20~2.93~4.10 2 ω = 65.14~39.89~23.95Surface number R D N_(d) ν_(d) 1 −267.083 1.39 1.69400 56.30 2 11.0852.29 — — 3 10.023 1.56 1.75211 25.05 4 25.674 1.50 — — 5 −10.134 0.601.71300 53.93 6 −93.913 12.45~5.48~1.15  — — 7 9.858 1.55 1.51680 64.208 −253.893 0.10 — — 9 6.030 1.99 1.48749 70.45 10 296.170 1.54 — — 11−48.736 0.60 1.80518 25.46 12 5.591 0.27 1.51576 52.63 HB 9.556 2.30 — —13 11.259 1.86 1.59270 35.45 14 −15.730 5.78~7.07~9.97 — — 15 −8.3541.20 1.51680 64.20 16 −17.033 0.62~3.47~7.00 — — 17 ∞ 0.64 1.54892 69.7618 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 1.58852E−03 B = −5.49799E−05 C =1.35002E−06 D = −1.65445E−08 E = 8.89968E−11 2^(nd) surface K =0.00000E+00 A = 1.73732E−03 B = −3.74083E−05 C = −2.45701E−07 D =4.40830E−08 E = −3.77383E−10 HB plane K = 0.00000E+00 A = 1.65275E−03 B= 2.44004E−05 C = 7.67809E−07

EMBODIMENT 3

A numerical example for a third embodiment of a zoom lens of theinvention will be shown in Table 3. In addition, FIG. 5 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 6is a diagram showing aberrations thereof.

TABLE 3 f = 7.16~12.08~20.34 F = 1.96~2.67~3.78 2 ω = 66.05~41.13~25.07Surface number R D N_(d) ν_(d) 1 15.847 0.72 1.82080 42.71 2 6.335 3.18— — 3 10.201 1.77 1.80518 25.46 4 31.687 1.58 — — 5 −11.002 0.60 1.7291654.66 6 −120.591 13.45~6.03~1.15  — — 7 16.318 1.54 1.59240 68.30 8−43.237 0.10 — — 9 5.818 2.44 1.49700 81.61 10 75.148 1.80 — — 112047.052 0.40 2.13120 24.07 12 8.259 0.08 1.51576 52.63 HB 11.960 2.25 —— 13 21.742 1.58 1.63980 34.57 11 −12.178  5.75~6.57~10.10 — — 15 −6.3120.86 1.52470 0.00 16 −9.915 0.59~3.83~6.50 — — 17 ∞ 0.64 1.54892 69.7618 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 7.71215E−04 B = −3.90277E−05 C =1.18125E−06 D = −1.67917E−08 E = 9.93339E−11 2^(nd) surface K =0.00000E+00 A = 6.01874E−04 B = −3.37703E−05 C = −2.01670E−07 D =4.13201E−08 E = −7.40014E−10 HB plane K = 0.00000E+00 A = 1.80140E−03 B= 1.85580E−05 C = 1.80175E−06 15^(th) surface K = 0.00000E+00 A =3.16319E−04 B = 2.25248E−05 C = −1.22537E−06 D = 3.38575E−08 E =7.76062E−10

EMBODIMENT 4

A numerical example for a fourth embodiment of a zoom lens of theinvention will be shown in Table 4. In addition, FIG. 7 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 8is a diagram showing aberrations thereof.

TABLE 4 f = 7.05~11.91~20.11 F = 1.96~2.67~3.77 2 ω = 66.82~41.71~25.41Surface number R D N_(d) ν_(d) 1 18.403 0.86 1.74330 49.33 2 6.257 3.09— — 3 10.128 1.76 1.75211 25.05 4 31.779 1.59 — — 5 −10.608 0.60 1.7725049.65 6 −49.451 13.36~6.01~1.15  — — 7 16.422 1.54 1.59240 68.30 8−42.611 0.10 — — 9 5.781 2.45 1.49700 81.61 10 73.135 1.73 — — 11230.193 0.40 2.13120 24.07 12 8.067 0.08 1.51576 52.63 HB 11.696 2.34 —— 13 22.222 1.56 1.64769 33.84 14 −12.637  5.79~6.59~10.16 — — 15 −6.3580.81 1.52470 0.00 16 −9.961 0.60~3.86~6.50 — — 17 ∞ 0.64 1.54892 69.7618 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 7.49568E−04 B = −3.53466E−05 C =1.04455E−06 D = −1.45700E−08 E = 8.45726E−11 2^(nd) surface K =0.00000E+00 A = 5.54774E−04 B = −2.80784E−05 C = −5.44305E−07 D =5.21552E−08 E = −8.89130E−10 HB plane K = 0.00000E+00 A = 1.80112E−03 B= 1.82356E−05 C = 2.03684E−06 15^(th) surface K = 0.00000E+00 A =3.10476E−04 B = 2.07038E−05 C = −1.23507E−06 D = 4.49982E−08 E =3.26333E−10

EMBODIMENT 5

A numerical example for a fifth embodiment of a zoom lens of theinvention will be shown in Table 5. In addition, FIG. 9 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 10is a diagram showing aberrations thereof.

TABLE 5 f = 7.32~12.36~20.86 F = 1.96~2.67~3.77 2 ω = 64.85~40.24~24.51Surface number R D N_(d) ν_(d) 1 15.627 0.72 1.80139 45.45 2 6.382 3.28— — 3 10.091 1.82 1.75211 25.05 4 34.848 1.48 — — 5 −11.446 0.60 1.7725049.65 6 −104.339 13.52~6.03~1.15  — — 7 13.018 1.55 1.59240 68.30 8−186.490 0.10 — — 9 6.245 2.43 1.49700 81.61 10 103.629 1.39 — — 1150.000 0.60 1.84666 23.78 12 6.284 0.27 1.51576 52.63 HB 11.765 2.68 — —13 77.186 1.18 1.72825 28.31 14 −16.362 5.54~6.28~9.90 — — 15 −6.2740.80 1.52470 0.00 16 −9.088 0.66~3.94~6.50 — — 17 ∞ 0.64 1.54892 69.7618 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 7.00066E−04 B = −3.49645E−05 C =1.05833E−06 D = −1.49056E−08 E = 8.68760E−11 2^(nd) surface K =0.00000E+00 A = 5.17317E−04 B = −2.82572E−05 C = −3.38472E−07 D =4.25868E−08 E = −7.40912E−10 HB plane K = 0.00000E+00 A = 1.57492E−03 B= 1.49192E−05 C = 2.33017E−06 15^(th) surface K = 0.00000E+00 A =3.07622E−04 B = 2.11729E−05 C = −4.37666E−07 D = −3.75725E−08 E =2.60868E−09

EMBODIMENT 6

A numerical example for a sixth embodiment of a zoom lens of theinvention will be shown in Table 6. In addition, FIG. 11 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 12is a diagram showing aberrations thereof.

TABLE 6 f = 7.50~12.67~21.38 F = 1.96~2.64~3.67 2 ω = 64.46~39.41~23.74Surface number R D N_(d) ν_(d) 1 24.732 0.72 1.80139 45.45 2 7.162 3.23— — 3 12.488 1.49 1.84666 23.78 4 51.817 1.73 — — 5 −8.938 0.60 1.7291654.66 6 −31.223 12.98~6.03~1.15  — — 7 23.748 1.20 1.56907 71.30 8 ∞0.10 — — 9 7.165 2.41 1.56907 71.30 10 48.475 1.68 — — 11 25.193 0.401.92286 20.88 12 8.143 0.28 1.51576 52.63 HB 16.145 2.57 — — 13 53.5461.55 1.59270 35.45 14 −14.324  8.41~9.04~14.94 — — 15 −15.561 0.941.48749 70.45 16 −56.216 0.85~5.00~6.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 5.24648E−04 B = −2.94471E−05 C =9.41191E−07 D = −1.29636E−08 E = 6.72139E−11 2^(nd) surface K =0.00000E+00 A = 2.78611E−04 B = −2.49964E−05 C = −2.50676E−07 D =4.13496E−08 E = −7.49035E−10 HB plane K = 0.00000E+00 A = 9.70290E−04 B= 1.32384E−05 C = 2.14344E−08 D = 2.39724E−08

EMBODIMENT 7

A numerical example for a seventh embodiment of a zoom lens of theinvention will be shown in Table 7. In addition, FIG. 13 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 14is a diagram showing aberrations thereof.

TABLE 7 f = 6.84~11.55~19.51 F = 1.96~2.71~3.87 2 ω = 69.08~42.81~26.10Surface number R D N_(d) ν_(d) 1 15.653 0.72 1.80139 45.45 2 6.040 2.70— — 3 9.350 1.85 1.75211 25.05 4 38.082 1.31 — — 5 −11.201 0.60 1.8042046.49 6 −244.422 11.13~5.11~1.15  — — 7 10.418 1.63 1.63246 63.80 8−56.708 0.10 — — 9 5.172 2.30 1.49700 81.61 10 24.537 0.56 — — 11 11.3190.60 2.13120 24.07 12 4.674 0.28 1.51576 52.63 HB 8.571 3.56 — — 1349.982 1.17 1.72825 28.32 14 −16.470 2.85~3.39~5.07 — — 15 −5.163 0.801.52470 56.24 16 −11.872 0.42~3.18~6.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 6.73986E−04 B = −3.42408E−05 C =1.13307E−06 D = −1.70404E−08 E = 1.08315E−10 2^(nd) surface K =0.00000E+00 A = 4.58940E−04 B = −2.49784E−05 C = −7.03415E−07 D =6.45140E−08 E = −1.11179E−09 HB plane K = 0.00000E+00 A = 2.46880E−03 B= 3.77422E−05 C = 9.84085E−06 15^(th) surface K = 0.00000E+00 A =8.07318E−04 B = −1.31471E−05 C = 6.51045E−06 D = −4.71874E−07 E =1.44714E−08

EMBODIMENT 8

A numerical example for an eighth embodiment of a zoom lens of theinvention will be shown in Table 8. In addition, FIG. 15 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 16is a diagram showing aberrations thereof.

TABLE 8 f = 6.31~10.65~17.98 F = 1.96~2.63~3.86 2 ω = 73.41~46.41~28.54Surface number R D N_(d) ν_(d) 1 17.015 0.72 1.80139 45.45 2 5.363 2.18— — 3 9.445 1.85 1.75211 25.05 4 58.657 1.21 — — 5 −10.533 0.60 1.8042046.49 6 −73.349 10.29~4.57~1.15  — — 7 9.281 1.60 1.63246 63.80 8−146.546 0.10 — — 9 5.000 2.20 1.56907 71.30 10 15.862 0.43 — — 11 8.6530.60 2.13120 24.07 12 4.035 0.28 1.51576 52.63 HB 6.778 3.80 — — 1310.273 1.16 1.64769 33.84 14 44.746 2.33~3.96~6.50 — — 15 −11.741 0.801.52470 56.24 16 −100.000 0.42~2.06~4.67 — — 17 ∞ 0.64 1.54892 69.76 18∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients1^(st) surface K = 0.00000E+00 A = 7.11482E−04 B = −4.64796E−05 C =1.77120E−06 D = −3.35921E−08 E = 2.73324E−10 2^(nd) surface K =0.00000E+00 A = 4.23375E−04 B = −6.38713E−05 C = 8.81002E−07 D =3.08608E−08 E = −1.74431E−09 HB plane K = 0.00000E+00 A = 2.66098E−03 B= 2.18014E−04 C = −2.03204E−05 D = 2.93539E−06 15^(th) surface K =0.00000E+00 A = −2.93208E−03 B = −1.27225E−03 C = 2.33560E−04 D =−1.67617E−05 E = 4.44737E−07 16^(th) surface K = 0.00000E+00 A =−4.12052E−03 B = −4.73899E−04 C = 9.24730E−05 D = −5.77245E−06 E =1.28099E−07

EMBODIMENT 9

A numerical example for a ninth embodiment of a zoom lens of theinvention will be shown in Table 9. In addition, FIG. 17 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 18is a diagram showing aberrations thereof.

TABLE 9 f = 6.74~11.38~19.21 F = 1.96~2.68~3.87 2 ω = 70.13~43.83~26.48Surface number R D N_(d) ν_(d) 1 36.140 0.72 1.80139 45.45 2 8.483 1.74— — 3 56.891 1.41 1.90680 21.20 4 −24.955 1.03 — — 5 −10.738 0.601.80420 46.49 6 −200.000 10.20~4.59~1.15  — — 7 8.042 1.84 1.49700 81.618 −68.006 0.10 — — 9 7.177 1.58 1.49700 81.61 10 172.553 1.58 — — 1111.875 0.60 1.94595 17.98 12 6.430 3.22 — — 13 6.958 1.38 1.59270 35.4514 25.063 2.82~3.74~5.23 — — 15 −10.314 1.20 1.69400 56.30 16 −100.0000.58~2.92~6.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.641.51680 64.20 20 ∞ — — — aspherical coefficients 1^(st) surface K =0.00000E+00 A = 4.98461E−04 B = −2.03601E−05 C = 7.01097E−07 D =−1.03245E−08 E = 5.90908E−11 2^(nd) surface K = 0.00000E+00 A =3.87140E−04 B = −1.30231E−05 C = −1.46782E−07 D = 3.28872E−08 E =−5.56360E−10 9^(th) surface K = 0.00000E+00 A = −3.14332E−04 B =2.43375E−08 C = −1.12574E−06 D = 1.85915E−08 10^(th) surface K =0.00000E+00 A = 3.04348E−04 B = −5.47777E−06 C = −5.02203E−07 D =1.54264E−08 15^(th) surface K = 0.00000E+00 A = −7.06471E−03 B =9.93684E−05 C = −7.12983E−06 D = 1.49799E−06 E = −7.81775E−08 16^(th)surface K = 0.00000E+00 A = −5.59290E−03 B = 2.40927E−04 C =−1.03510E−05 D = 5.98947E−07 E = −1.89781E−08

EMBODIMENT 10

A numerical example for a 10th embodiment of a zoom lens of theinvention will be shown in Table 10. In addition, FIG. 19 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 20is a diagram showing aberrations thereof.

TABLE 10 f = 6.34~10.72~18.08 F = 1.96~2.56~3.56 2 ω = 73.38~45.12~27.42Surface number R D N_(d) ν_(d) 1 18.462 0.73 1.80139 45.45 2 5.886 3.15— — 3 10.180 1.74 1.80518 25.46 4 33.752 1.57 — — 5 −10.151 0.60 1.7130053.93 6 −43.539 14.00~5.92~1.15 — — 7 9.569 1.96 1.48749 70.45 8−169.263 0.10 — — 9 6.063 2.30 1.49700 81.61 10 251.755 0.27 — — 119.793 0.44 2.13120 24.07 12 5.562 2.00 — — 13 −29.901 1.19 1.58144 40.8914 −9.099 7.59~11.45~17.93 — — 15 −28.509 0.77 1.80139 45.45 16 −100.0000.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.2020 ∞ — — — aspherical coefficients 1^(st) surface K = 0.00000E+00 A =9.57722E−04 B = −6.34113E−05 C = 2.14801E−06 D = −3.42100E−08 E =2.15103E−10 2^(nd) surface K = 0.00000E+00 A = 7.56659E−04 B =−6.70163E−05 C = 1.68608E−07 D = 7.76286E−08 E = −1.91822E−09 9^(th)surface K = 0.00000E+00 A = −1.40806E−04 B = 3.06302E−06 C =−1.81087E−07 D = 3.31558E−09 10^(th) surface K = 0.00000E+00 A =9.68134E−04 B = −3.49836E−06 C = −7.95269E−08 D = 5.61073E−09 15^(th)surface K = 0.00000E+00 A = −2.91282E−03 B = 3.46542E−04 C =−1.06580E−05 16^(th) surface K = 0.00000E+00 A = −3.01357E−03 B =2.99577E−04 C = −482336E−06 D = −1.55216E−07

EMBODIMENT 11

A numerical example for an 11th embodiment of a zoom lens of theinvention will be shown in Table 11. In addition, FIG. 21 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 22is a diagram showing aberrations thereof.

TABLE 11 f = 6.71~11.33~19.11 F = 1.96~2.58~3.67 2ω = 70.19~43.46~26.13Surface number R D N_(d) ν_(d) 1 19.622 0.72 1.80139 45.45 2 6.259 2.66— — 3 9.860 1.50 1.92286 20.88 4 16.423 2.52 — — 5 −9.063 0.60 1.7291654.66 6 −18.779 14.00~5.92~1.15 — — 7 8.982 2.15 1.49700 81.61 8−100.000 0.10 — — 9 6.397 2.84 1.49700 81.61 10 26.611 1.07 — — 1116.986 0.46 2.13120 24.07 12 5.793 1.78 — — 13 10.614 1.80 1.59270 35.4514 −16.340 7.23~11.54~18.80 — — 15 −9.688 0.60 1.77250 49.65 16 −13.2800.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.2020 ∞ — — — aspherical coefficients 1^(st) surface 2^(nd) surface K =0.00000E+00 K = 0.00000E+00 A = 7.65552E−04 A = 6.40643E−04 B =−3.73883E−05 B = −4.06795E−05 C = 1.05806E−06 C = 3.14200E−07 D =−1.44013E−08 D = 1.86716E−08 E = 8.24195E−11 E = −4.30497E−10 9^(th)surface 10^(th) surface K = 0.00000E+00 K = 0.00000E+00 A = −9.82365E−05A = 6.50969E−04 B = −1.65981E−06 B = 7.92004E−06 C = 1.11062E−07 C =−6.07931E−07 D = −8.98355E−09 D = 1.03289E−08

EMBODIMENT 12

A numerical example for a 12th embodiment of a zoom lens of theinvention will be shown in Table 12. In addition, FIG. 23 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 24is a diagram showing aberrations thereof.

TABLE 12 f = 7.50~12.66~21.38 F = 1.96~2.64~3.74 2ω = 64.22~39.44~23.82Surface number R D N_(d) ν_(d) 1 27.549 1.41 1.92110 22.40 2 8.142 2.25— — 3 10.099 1.85 1.94595 17.98 4 26.525 1.78 — — 5 −11.762 0.60 1.7291654.66 6 −166.667 14.00~6.13~1.15 — — 7 8.538 1.96 1.56907 71.30 8 0.0000.10 — — 9 7.083 2.15 1.49700 81.61 10 33.148 2.11 — — 11 −22.428 0.601.92110 22.40 12 11.132 1.49 — — 13 12.933 1.80 1.59270 35.45 14 −11.4105.39~6.38~9.37 — — 15 −6.312 0.80 1.52470 56.24 16 −9.596 0.65~3.49~6.50— — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.64 1.51680 64.20 20 ∞ —— — aspherical coefficients 1^(st) surface 2^(nd) surface K =0.00000E+00 K = 0.00000E+00 A = 8.23589E−04 A = 9.18013E−04 B =−2.32953E−05 B = −1.56289E−05 C = 4.76324E−07 C = −3.09049E−07 D =−4.68996E−09 D = 2.31994E−08 E = 2.00330E−11 E = −2.15404E−10 12^(th)surface 15^(th) surface K = 0.00000E+00 K = 0.00000E+00 A = 1.06746E−03A = 1.48298E−04 B = 4.78234E−06 B = 4.39621E−05 C = 5.17213E−07 C =−4.31510E−06 D = −3.58877E−09 D = 2.34094E−07 E = −4.28919E−09

EMBODIMENT 13

A numerical example for a 13th embodiment of a zoom lens of theinvention will be shown in Table 13. In addition, FIG. 25 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 26is a diagram showing aberrations thereof.

TABLE 13 f = 7.45~12.58~21.23 F = 1.96~2.69~3.89 2ω = 64.57~39.80~24.08Surface number R D N_(d) ν_(d) 1 17.811 0.72 1.81474 37.03 2 6.504 3.14— — 3 10.745 1.74 1.84666 23.78 4 40.771 1.49 — — 5 −10.771 0.60 1.7130053.93 6 −254.187 12.99~5.79~1.15 — — 7 7.909 2.57 1.63246 63.80 8−19.247 0.33 — — 9 6.575 1.77 1.49700 81.61 10(11) 33.647 0.60 2.0816030.38 12 5.624 2.94 — — 13 27.585 1.49 1.51742 52.15 14 −10.4216.28~7.32~11.42 — — 15 −6.326 1.02 1.52470 56.24 16 −8.8360.67~3.94~6.50 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.641.51680 64.20 20 ∞ — — — aspherical coefficients 1^(st) surface 2^(nd)surface 7^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A= 5.60092E−04 A = 3.49256E−04 A = −2.07419E−04 B = −2.82891E−05 B =−2.58974E−05 B = −2.23611E−06 C = 8.47721E−07 C = −1.55937E−07 C =−1.42245E−08 D = −1.16415E−08 D = 2.87711E−08 D = 1.03618E−09 E =6.74009E−11 E = −5.02015E−10 8^(th) surface 15^(th) surface K =0.00000E+00 K = 0.00000E+00 A = 3.03841E−04 A = 2.10416E−04 B =−4.33614E−06 B = 2.52471E−05 C = 9.06291E−08 C = −2.26441E−06 D =1.20990E−07 E = −1.65381E−09

EMBODIMENT 14

A numerical example for a 14th embodiment of a zoom lens of theinvention will be shown in Table 14. In addition, FIG. 27 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 28is a diagram showing aberrations thereof.

TABLE 14 f = 6.57~11.09~18.74 F = 1.96~2.67~3.87 2ω = 71.53~44.99~27.19Surface number R D N_(d) ν_(d) 1 38.088 0.72 1.80139 45.45 2 10.760 1.68— — 3 38.575 1.32 1.90680 21.20 4 −42.703 0.80 — — 5 −13.194 0.601.69400 56.30 6 19.949 9.87~4.64~1.40 — — 7 7.492 1.97 1.49700 81.61 8−29.304 0.10 — — 9 8.036 1.42 1.49700 81.61 10 148.276 1.65 — — 1119.507 0.60 1.94595 17.98 12 8.199 3.09 — — 13 6.795 1.46 1.59270 35.4514 40.999 2.33~3.27~4.80 — — 15 −9.861 1.20 1.74330 49.33 16 −99.9880.80~3.09~6.52 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.641.51680 64.20 20 ∞ — — — aspherical coefficients 1^(st) surface 2^(nd)surface 9^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A= 1.01570E−03 A = 1.05848E−03 A = −8.71380E−04 B = −2.41130E−05 B =−1.21429E−05 B = −4.11912E−05 C = 3.68148E−07 C = −2.28661E−07 C =−2.00496E−06 D = −5.16203E−10 D = 1.01210E−08 D = −8.00461E−08 E =−2.55290E−12 E = 2.10694E−10 10^(th) surface 15^(th) surface 16^(th)surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A = −4.73025E−04A = −8.22096E−03 A = −6.40932E−03 B = −4.68723E−05 B = 1.04367E−04 B =3.04870E−04 C = −1.46586E−06 C = 9.03387E−06 C = −9.58281E−06 D =−1.85909E−08 D = −9.34746E−07 D = 2.27246E−07 E = 5.93470E−08 E =−1.47484E−09

EMBODIMENT 15

A numerical example for a 15th embodiment of a zoom lens of theinvention will be shown in Table 15. In addition, FIG. 29 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 30is a diagram showing aberrations thereof.

TABLE 15 f = 6.49~10.96~18.51 F = 1.96~2.61~3.73 2ω = 71.73~44.92~27.28Surface number R D N_(d) ν_(d) 1 98.945 1.50 1.76802 49.24 2 7.890 1.00— — 3 7.292 1.85 1.75211 25.05 4 15.697 1.50 — — 5 −11.908 0.60 1.6940056.30 6 180.979 10.09~4.50~1.23 — — 7 8.578 1.59 1.72916 54.66 8 −92.3800.20 — — 9 5.608 1.55 1.56907 71.30 10 20.974 0.43 — — HB 8.560 0.281.51576 52.63 11 26.836 0.40 2.13120 24.07 12 5.623 4.22 — — 13 8.1191.47 1.67270 32.17 14 45.144 2.55~3.80~5.34 — — 15 60.959 0.80 1.5247056.24 16 10.937 0.55~2.65~6.41 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — —19 ∞ 0.64 1.51680 64.20 20 ∞ — — — aspherical coefficients 1^(st)surface 2^(nd) surface HB plane K = 0.00000E+00 K = 0.00000E+00 K =0.00000E+00 A = 1.76253E−03 A = 2.17723E−03 A = −1.21189E−03 B =−6.27228E−05 B = −3.32205E−05 B = −2.93147E−05 C = 1.53123E−06 C =−1.01399E−06 C = 6.04242E−07 D = −1.91070E−08 D = 8.46611E−08 D =−2.12874E−08 E = 9.93692E−11 E = −5.29309E−10 15^(th) surface 16^(th)surface K = 0.00000E+00 K = 0.00000E+00 A = −1.07470E−02 A =−1.03696E−02 B = 3.29717E−04 B = 5.29364E−04 C = −5.84664E−06 C =−1.77903E−05 D = 5.46775E−07 D = 4.90408E−07 E = −4.53815E−08 E =−1.46981E−08

EMBODIMENT 16

A numerical example for a 16th embodiment of a zoom lens of theinvention will be shown in Table 16. In addition, FIG. 31 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 32is a diagram showing aberrations thereof.

TABLE 16 f = 5.80~9.79~16.53 F = 1.96~2.64~3.79 2ω = 77.96~50.42~30.92Surface number R D N_(d) ν_(d) 1 28.033 0.72 1.80139 45.45 2 7.946 1.60— — 3 18.082 1.51 1.90680 21.20 4 −124.335 0.67 — — 5 −15.650 0.601.71300 53.93 6 15.749 9.69~4.58~1.43 — — 7 7.006 1.79 1.51680 64.20 8−34.445 0.10 — — 9 8.888 1.72 1.48749 70.45 10 −25.459 0.76 — — 1194.713 0.60 1.94595 17.98 12 10.602 3.53 — — 13 7.168 1.42 1.59270 35.4514 42.718 2.33~3.39~5.17 — — 15 −85.497 1.50 1.52470 56.24 16 9.7690.44~2.43~5.36 — — 17 ∞ 0.64 1.54892 69.76 18 ∞ 0.64 — — 19 ∞ 0.641.51680 64.20 20 ∞ — — — aspherical coefficients 1^(st) surface 2^(nd)surface 9^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A= 8.67478E−04 A = 7.89734E−04 A = −1.12725E−03 B = −2.29069E−05 B =−3.88424E−06 B = −6.89841E−05 C = 4.18462E−07 C = −8.96630E−07 C =−4.63941E−07 D = −3.71746E−09 D = 3.55035E−08 D = −1.62051E−07 E =1.75344E−11 E = −3.56438E−10 10^(th) surface 15^(th) surface 16^(th)surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A = −5.87874E−04A = −1.17541E−02 A = −1.07772E−02 B = −8.31786E−05 B = 3.57416E−04 B =6.05058E−04 C = 2.77664E−06 C = −5.86048E−05 C = −3.89222E−05 D =−1.93492E−07 D = 5.75674E−06 D = 2.04301E−06 E = −2.09336E−07 E =−4.97521E−08

Next, with respect to Embodiments 1 to 16, values corresponding to theconditional expressions (1) to (15) will altogether be shown in Table17.

TABLE 17 Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment5 Conditional expression (1) −0.58 −0.63 −0.59 −0.59 −0.58 Conditionalexpression (2) 5.94 5.32 5.68 5.76 5.55 Conditional expression (3) −0.19−0.22 −0.20 −0.19 −0.17 Conditional expression (4) 0.34 0.35 0.40 0.370.40 Conditional expression (5) 24.48 30.07 23.23 24.44 22.50Conditional expression (6) 1.85 1.75 1.81 1.75 1.75 Conditionalexpression (7) 1.03 0.67 1.13 1.13 1.15 Conditional expression (8) 0.641.11 0.62 0.62 0.63 Conditional expression (9) 0.88 0.96 0.91 0.90 0.88Conditional expression (10) −0.87 −0.92 −0.84 −0.81 −0.58 Conditionalexpression (11) 48.63 41.87 50.88 50.88 51.17 Conditional expression(12) −0.57 −0.30 −0.59 −0.59 −0.30 Conditional expression (13) 0.47 0.750.44 0.43 0.56 Conditional expression (14) 0.65 0.78 0.60 0.60 0.62Conditional expression (15) −1.07 −0.89 −1.13 −1.11 −1.17 EmbodimentEmbodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 10 Conditionalexpression (1) −0.65 −0.59 −0.63 −0.64 −0.56 Conditional expression (2)5.79 5.05 5.16 4.83 6.48 Conditional expression (3) −0.17 −0.38 −0.25−0.40 −0.13 Conditional expression (4) 0.39 0.43 0.43 0.35 0.36Conditional expression (5) 26.27 20.92 20.92 24.77 24.24 Conditionalexpression (6) 1.85 1.75 1.75 1.91 1.81 Conditional expression (7) 1.051.13 1.18 0.79 1.08 Conditional expression (8) 0.57 0.65 0.57 0.15 0.58Conditional expression (9) 0.69 1.00 0.97 0.88 0.81 Conditionalexpression (10) −0.34 −0.59 −0.57 −0.43 −0.53 Conditional expression(11) 50.42 48.63 43.48 63.63 51.96 Conditional expression (12) −0.35−0.57 −0.53 −0.45 −0.64 Conditional expression (13) 0.32 0.66 0.68 0.840.66 Conditional expression (14) 0.46 0.80 0.93 1.05 1.14 Conditionalexpression (15) −0.48 −1.32 −0.54 −0.65 −0.22 Embodiment EmbodimentEmbodiment Embodiment Embodiment Embodiment 11 12 13 14 15 16Conditional expression (1) −0.61 −0.56 −0.62 −0.66 −0.63 −0.64Conditional expression (2) 6.40 5.45 5.41 4.81 5.02 5.34 Conditionalexpression (3) −0.13 −0.20 −0.15 −0.44 −0.25 −0.35 Conditionalexpression (4) 0.28 0.46 0.44 0.29 0.39 0.33 Conditional expression (5)29.19 20.55 21.70 29.68 27.73 28.49 Conditional expression (6) 1.92 1.951.85 1.91 1.75 1.91 Conditional expression (7) 1.07 0.92 1.15 0.61 0.820.73 Conditional expression (8) 0.63 0.81 0.61 0.28 1.08 0.44Conditional expression (9) 0.80 0.90 1.21 0.89 1.07 0.88 Conditionalexpression (10) −0.84 −0.94 −1.18 −0.43 −0.73 −0.46 Conditionalexpression (11) 57.54 54.05 42.32 63.63 38.91 49.34 Conditionalexpression (12) −0.63 −0.39 −0.52 −0.45 −0.48 −0.44 Conditionalexpression (13) 0.75 0.88 0.94 0.88 0.76 0.83 Conditional expression(14) 1.16 0.67 1.32 0.80 1.15 0.55 Conditional expression (15) −0.69−1.19 −1.18 −0.67 0.11 −0.07

As is obvious from Table 17, the values for each embodiment fromEmbodiments 1 to 16 satisfy the conditional expressions (1) to (15), andas is obvious from the aberration diagrams of each embodiment, theindividual aberrations are corrected properly.

Next, Embodiments 17 to 24 of the invention will be described byreference to specific numerical examples thereof.

Also, in Embodiments 17 to 24which will be described below, a zoom lensis made up of, sequentially from an object side thereof, a first lenselements group LG1, a second lens elements group LG2 and a third lenselement group LG3.

The first lens elements group LG1 has a negative refraction power as awhole and is made up by disposing a first lens element L1 (an objectside surface of the first lens element L1 is to be referred to as a1^(st) surface, and an image side surface as a 2^(nd) surface) which isa lens having a negative refraction power (hereinafter referred to as anegative lens) and which has a meniscus configuration which is convex onthe object side surface, a second lens element L2 (an object sidesurface of the second lens element L2 is to be referred to as a 3^(rd)surface, and an image side surface as a 4^(th) surface) which is a lenshaving a positive refraction power (hereinafter, referred to as apositive lens) and which has a meniscus configuration which is convex onthe object side surface, and a third lens element L3 (an object sidesurface of the third lens element L3 is to be referred to as a 5^(th)surface, and an image side surface as a 6^(th) surface) which is anegative lens.

The second lens elements group LG2 has a positive refraction power as awhole and is made up by disposing a fourth lens element L4 (an objectside surface of the fourth lens element L4 is to be referred to as a7^(th) surface, and an image side surface as an 8^(th) surface) which isa positive lens, a fifth lens element L5 (an object side surface of thefifth lens element L5 is to be referred to as a 9^(th) surface, and animage side surface as a 10^(th) surface) which is a negative lens andwhich has a meniscus configuration which is convex on the object sidesurface, and a sixth lens element L6 (an object side surface of thesixth lens element L6 is referred to be as an 11^(th) surface and animage side surface as a 12^(th) surface) which is a positive lens.

The third lens element group LG3 has a negative refraction power as awhole and is made up by disposing a seventh lens element L7 (an objectside surface of the seventh lens element L7 is to be referred to as a13^(th) surface, and an image side surface as a 14^(th) surface) whichis a negative lens.

In addition, a crystal optical filter LPF (an object side surface of thecrystal optical filter LPF is to be referred to as a 15^(th) surface,and an image side surface as an 16^(th) surface) and a cover glass CG(an object side surface of the cover glass CG is to be referred to as a17^(th) surface, and an image side surface as an 18^(th) surface) whichis for protection of a photographic portion of a CCD are disposed withinan air space defined between the image side surface, which is the14^(th) surface, of the seventh lens element L7 and an image plane.

The cutting of infrared rays which is required in handling an imagesensor such as a CCD is understood to be implemented by applying aninfrared reflection coating on to one side of refracting surfaces of thecrystal optical filter LPF and, hence, is not illustrated.

A variable power is realized by shifting the positions of the first lenselements group LG1 and the second lens elements group LG2 in a directionof an optical axis of the zoom lens, or shifting, in addition to thefirst lens elements group LG1 and the second lens elements group LG2,the position of the third lens element group LG3.

In addition, in each embodiment, although a focal point adjustment foran object at a finite distance can be realized by shifting the positionof the first lens elements group LG1 or the third lens element group LG3in the direction of the optical axis, the implementation of focal pointadjustment is not limited to the relevant method.

Furthermore, the shape of an aspheric surface used in each embodiment isdefined as is known by giving a paraxial radius of curvature: R, a conicconstant: K and high-order aspherical coefficients: A, B, C, D on acurved surface that is obtained by rotating round the optical axis acurve given by an aspherical equation:

Z=(Y ² /R)/[1+√{1−(1+K)(Y/R)² }]+A·Y ⁴ +B·Y ⁶ +C·Y ⁸ +C·Y ¹⁰+. . .

when the Z axis is taken in the direction of the optical axis and the Yaxis is taken in a direction which intersects the optical axis at rightangles. Note that in the description of conic constants and high-orderaspherical coefficients in tables, “E and numerals which follow it”represents an “exponent of 10.” For example, “E-04” means 10⁻⁴, and anumber just before it is multiplied by this number.

In addition, this embodiment, which is made up of the seven lenselements, satisfies the following conditional expression (16) withrespect to the power that the first lens element group possesses, thefollowing conditional expression (17) with respect to the size of thewhole lens system, and the following conditional expression (18) withrespect to the power that the third lens element group possesses.

−0.8≦f _(w) /f _(I)≦−0.4   (16)

4.5≦TL _(w) /f _(w)≦7.5   (17)

−0.6≦f _(w) /f _(III)≦0   (18)

where,

f_(w): composite focal length of the whole lens system at wide-angle end

f_(I): composite focal length of the first lens element group

f_(III): composite focal length of the third lens element group

TL_(w): distance from an object side surface of the first lens elementmaking up the first lens elements group to the image plane at wide-angleend (where, a parallel plane glass portion is converted into an airspace distance).

The conditional expression (16) relates to a proper distribution ofpower to the first lens element group which has the negative power. Theconditional expression (16) specifies a condition for providing awell-balanced solution to properly correct the size and aberrations ofthe whole optical system and is substantially similar to the conditionalexpression (1) for Embodiments 1 to 16 that have been described before.

The conditional expression (17) is such as to control the overall lengthof the zoom lens at the wide-angle end. Namely, this expressionspecifies a condition which becomes a measure of reduction in size ofthe zoom lens of the invention and provides a similar condition to thecondition for Embodiments 1 to 16 that have been described before. Thisconditional expression (17) has the same numerical range as that of theconditional expression (2).

The third conditional expression (18) is a conditional expression whichis related to the power that the third lens element group possesses. Itis a prime characteristic that it remains within the negative range,whereby a function is provided to cause the exit pupil of the opticalsystem to approach the image plane side. This conditional expression(18) is substantially similar to the conditional expression (3) forEmbodiments 1 to 16 that have been described before.

In addition, in the case of this embodiment, since by giving thenegative power to the third lens element group, the change in angle ofthe principal ray of light when changing the magnification becomes about2.6° to 4.6°, which is extremely small compared to the correspondingamount of change of a zoom lens of normal type in which the third lenselements group has a positive power, a large angle can be taken for theprincipal ray of light.

In embodiments to be described later on in which seven lens elements areprovided, the angle of a principal ray of light (when a bisector of anangle formed by an upper ray of light and a lower ray of light isdefined as a principal ray of light) at a maximum image point on thepicture plane is limited to be a maximum of 18°, and a lower limit valuethat is specified by the conditional expression of the conditionalexpression (18) is to be a range where the negative power of the thirdlens element group can be taken in that state. When the lower limit issurpassed, although it is effective in making the system compact, theangle of the principal ray exceeds 20°, and problems are caused ofshading and insufficient quantity of light, whereby the high imagequality required for a digital still camera or the like becomes unableto be maintained. On the contrary, when an upper limit is surpassed, itmeans that an optical system of a size results which does not have to bemade compact by the application of the invention.

In addition, in this embodiment, the first lens element which makes upthe first lens elements group is an aspherical lens, and this embodimentsatisfies the following conditional expression (19) with respect to thepower that the second lens element possesses, the following conditionalexpression (20) with respect to the dispersion properties that aredistributed to each lens element of the first lens elements group, thefollowing conditional expression (21) with respect to the refractiveindex of the second lens element, the following conditional expression(22) with respect to the configuration of the image side surface of thefirst lens element, and satisfies the following conditional expression(23) with respect to a relative characteristic on configuration betweenthe image side surface of the first lens element and the object sidesurface of the second lens element.

0.25≦f _(w) /f ₂≦0.55   (19)

15≦(ν₁+ν₃)/2−ν₂   (20)

1.65≦n₂   (21)

0.8≦f _(w) /r ₂≦1.5   (22)

0.45≦r ₂ /r ₃≦0.85   (23)

where,

f₂: focal length of the second lens element which makes up the firstlens elements group

ν₁: Abbe number of the first lens element which makes up the first lenselements group

ν₂: Abbe number of the second lens element which makes up the first lenselements group

ν₃: Abbe number of the third lens element which makes up the first lenselements group

n₂: refractive index relative to the d line of the second lens elementwhich makes up the first lens elements group

r₂: radius of curvature of the image side surface of the first lenselement which makes up the first lens elements group

r₃: radius of curvature of the object side surface of the second lenselement which makes up the first lens elements group.

The conditional expression (19) is substantially similar to theconditional expression (4) for Embodiments 1 to 16 that have beendescribed before in that the former expression also specifies arequirement for correcting properly basic aberrations of the first lenselements group as a whole.

The conditional expression (20) relates to the distribution of Abbenumbers of the negative lenses and the positive lens which make up thefirst lens elements group and specifies a similar condition to thecondition for Embodiments 1 to 16 that have been described above. Thisconditional expression (20) has the same numerical range as that of theconditional expression (5).

In addition, the conditional expression (21) specifies a condition forcorrection of curvature of field and is substantially similar to theconditional expression (6) for Embodiments 1 to 16 that have beendescribed before.

A basic configuration for suppressing the occurrence of off-axisaberrations such as coma aberration and distortion is realized byproviding a concentric configuration relative to the entrance pupilunder the strong negative power which is imparted to the first lenselement, and the conditional expression (22) specifies a condition forrealizing the relevant configuration and is substantially similar to theconditional expression (7) for Embodiments 1 to 16 that have beendescribed above.

The conditional expression (23) is a conditional expression forcorrecting properly a positive spherical aberration that is caused by astrong diverging action occurring on the image side surface of the firstlens element having the negative power.

In the event that an upper limit is surpassed, a negative sphericalaberration by the second lens element becomes excessive, and on thecontrary, in the event that a lower limit is surpassed, the positivespherical aberration by the first lens element becomes excessive,whereby in either of the cases, the spherical aberrations cannot becorrected properly.

Furthermore, in this embodiment, of refracting surfaces of each lenselement which makes up the second lens elements group, at least one ofthe refracting surfaces is formed into an aspherical shape, and thisembodiment satisfies the following conditional expression (24) withrespect to the positive power that the fourth lens element possesses,the following conditional expression (25) with respect to the negativepower that the fifth lens element possesses, and the followingconditional expression (26) with respect the dispersion properties thatare distributed to each lens element which makes up the second lenselements group, the following conditional expression (27) with respectto the refractive index that each of the similar lens elementspossesses, the following conditional expression (28) with respect to theconfiguration of the object side surface of the fourth lens element andthe following conditional expression (29) with respect to a relativerelationship between the configuration of the object side surface of thefourth lens element and the configuration of an image side surface ofthe sixth lens element.

0.65≦f _(w) /f ₄≦1.05   (24)

−0.5≦f _(w) /f ₅≦−0.3   (25)

25≦(ν₄+ν₆)/2−ν₅   (26)

−0.45≦(n ₄ +n ₆)/2−n ₅≦−0.20   (27)

0.8≦f _(w) /r ₇≦1.3   (28)

−1.1≦r ₇ /r ₁₂≦−0.7   (29)

where,

f₄: focal length of the fourth lens element which makes up the secondlens elements group

f₅: focal length of the fifth lens element which makes up the secondlens elements group

ν₄: Abbe number of the fourth lens element which makes up the secondlens elements group

ν₅: Abbe number of the fifth lens element which makes up the second lenselements group

ν₆: Abbe number of the sixth lens element which makes up the second lenselements group

n₄: refractive index relative to the d line of the fourth lens elementwhich makes up the second lens elements group

n₅: refractive index relative to the d line of the fifth lens elementwhich makes up the second lens elements group

n₆: refractive index relative to the d line of the sixth lens elementwhich makes up the second lens elements group

r₇: radius of curvature of the object side surface of the fourth lenselement which makes up the second lens elements group

r₁₂: radius of curvature of the image side surface of the sixth lenselement which makes up the second lens elements group.

The conditional expression (24) relates to the power of the fourth lenselement which is disposed closest to the object side in the second lenselements group and which has the strong positive power, the fourth lenselement being used in place of the fourth lens elements and the fifthlens elements in Embodiments 1 to 16 that have been described above.This conditional expression (24) specifies conditions for imparting alarge positive power for collecting rays of light which diverge from thefirst lens elements group and properly correcting the aberrations.

In the event that an upper limit is surpassed, the positive powerbecomes excessive, and at the same time, the spherical aberration iscorrected insufficiently, and on the contrary, in the event that a lowerlimit is surpassed, the positive power for collecting light rays fromthe first lens elements group becomes insufficient, and an excessivecorrection of spherical aberration results. In either of the cases,however, in addition to spherical aberration, the off-axis aberrationsuch as coma aberration and chromatic aberration are largely affected.

The conditional expression (25) relates to the power of the negativelens which makes up the second lens elements group and specifies a primerequirement for correction of the basic chromatic aberration andcurvature of field of the second lens elements group as a whole. Namely,in the event that an upper limit is surpassed, although a lensconfiguration made up of a combination in which the powers of therespective lens elements of the second lens elements group are small,the correction of chromatic aberration and curvature of field becomesinsufficient, and on the contrary, in the event a lower limit issurpassed, since each lens power becomes excessive, high-order sphericalaberration and coma aberration are produced, and a good performancecannot be obtained.

The conditional expression (26) relates to the distribution of Abbenumbers of the positive lens and the negative lens which is to be takeninto consideration in determining a glass material for each lens elementof the second lens elements group. Namely, the conditional expression(26) specifies a condition for keeping a balance with each aberrationwhile properly correcting the chromatic aberration of the whole lenssystem. In the event that a lower limit is surpassed, the power of eachlens element has to be increased so as to correct the chromaticaberration, and this will constitute a disadvantageous condition incorrecting the spherical aberration and coma aberration.

The conditional expression (27) relates to the correction of curvatureof field in the second lens elements group. In order to balance anegative Petzval sum produced from the first lens elements group, therefractive index of each lens element needs to be a value which fallswithin a range specified by a condition presented by the relevantexpression. In the event that an upper limit is surpassed, the Petzvalsum becomes too small, and the balance with the spherical aberration islost, causing the correction of curvature of field to become excessive.Similarly, a lower unit is surpassed, the correction of curvature offield becomes insufficient, and the performance of the whole pictureplane cannot be maintained.

In addition, the conditional expression (28) is a conditional expressionin relation to the configuration of the object side surface of thefourth lens element. Since the object side surface of the fourth lenselement is disposed right behind an aperture stop, the relevant surfaceplays an important role in correcting spherical aberration. Theconditional expression (28) specifies a condition for properlycorrecting spherical aberration in connection with the negative power ofthe first lens elements group.

In the event that an upper limit of the conditional expression (28) issurpassed, although off-axis aberrations such as coma aberration andastigmatism get easy to be corrected, an insufficient correction ofspherical aberration results. On the contrary, in the event that a lowerlimit is surpassed, an excessive correction of spherical aberrationresults, and at the same time, a proper correction of the off-axisaberrations becomes difficult.

The conditional expression (29) is, along with the conditionalexpression (28), a conditional expression which corrects sphericalaberration and other aberrations in a balanced fashion. In the eventthat an upper limit is surpassed, the correction of aberrations becomesdifficult, and on the contrary, in the event that a lower limit issurpassed, a proper correction of spherical aberration is disabled.

In addition, the embodiment satisfies the following conditionalexpression (30) with respect to the configuration of the object sidesurface of the seventh lens element which makes up the third lenselement group.

−1.2≦f _(w) /r ₁₃≦0.4   (30)

where,

r₁₃: radius of curvature of the object side surface of the seventh lenselement which makes up the third lens element group.

As is shown by the conditional expression (30), in order to cause raysof light converging from the second lens elements group to focus on animage plane with production of little aberration, basically, theconfiguration of the object side surface of the seventh lens element ispreferably formed into a concentric shape relative to the second lenselements group.

Consequently, although it is good that the value of the conditionalexpression (30) basically takes a negative value, depending on designspecifications such as overall length, in the event that the relevantsurface is an aspherical surface, as is shown at an upper limit of theconditional expression (30), there may occur a case where the expressiontakes at least a positive value. However, in the event that the valuesurpasses an upper limit to become too large, both the peripheral shapeand the concentric shape are changed, whereby aberrations such as commaaberration and distortion are produced. In the event that a lower limitis surpassed, the Petzval sum due to the object side surface of theseventh lens element becomes too large on the negative side, and theangle of an emerging ray of light also becomes excessive.

EMBODIMENT 17

A numerical example for a 17th embodiment of a zoom lens of theinvention will be shown in Table 18. In addition, FIG. 33 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 34is a diagram showing aberrations thereof. In the table and figures, fdenotes the focal length of a whole lens system (hereinafter, valuesshown therein are from the left-hand side values at a wide-angle end,intermediate area and telephoto end), F_(no) ƒ number, and 2ω totalangle of view of lens. In addition, R denotes radius of curvature, Dlens element thickness or lens element space, N_(d) refractive index ofd line, and ν_(d) Abbe number of d line. In diagrams showingaberrations, d, g, C in diagrams showing spherical aberrations denoteaberration curves in individual wavelengths. In addition, S.C. denotessine condition. In astigmatism diagrams, S denotes sagital, and Mdenotes meridional.

TABLE 18 f = 7.06~11.92~20.10 F = 1.96~2.59~3.60 2ω = 67.41~41.42~25.07Surface number R D N_(d) ν_(d) 1 16.729 0.72 1.81474 37.03 2 6.464 3.52— — 3 11.169 1.67 1.84666 23.78 4 42.179 1.39 — — 5 −11.183 0.60 1.7130053.93 6 −218.787 13.77~6.15~1.15 — — 7 6.828 2.63 1.56907 71.30 8−17.616 1.00 — — 9 10.138 0.67 1.92286 20.88 10 5.946 2.28 — — 11−32.449 1.37 1.51680 64.20 12 −8.425 7.59~8.07~12.02 — — 13 −12.285 0.801.52470 56.24 14 −23.623 0.79~4.28~6.50 — — 15 ∞ 0.64 1.54892 69.76 16 ∞0.64 — — 17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients1^(st) surface 2^(nd) surface 7^(th) surface K = 0.00000E+00 K =0.00000E+00 K = 0.00000E+00 A = 4.78485E−04 A = 2.48666E−04 A =−3.98997E−04 B = −2.71492E−05 B = −2.59409E−05 B = −8.90933E−07 C =8.50633E−07 C = −1.25078E−07 C = −2.60573E−08 D = −1.21986E−08 D =2.89371E−08 D = −9.58774E−10 E = 7.20010E−11 E = −5.65562E−10 8^(th)surface 13^(th) surface K = 0.00000E+00 K = 0.00000E+00 A = 4.76749E−04A = 1.22023E−04 B = −2.35319E−06 B = −3.67055E−05 C = 5.30018E−08 C =5.84669E−06 D = −3.87348E−07 E = 9.48144E−09

EMBODIMENT 18

A numerical example for an 18th embodiment of a zoom lens of theinvention will be shown in Table 19. In addition, FIG. 35 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 36is a diagram showing aberrations thereof.

TABLE 19 f = 6.60~11.16~18.82 F = 1.96~2.59~3.66 2ω = 71.47~44.07~26.69Surface number R D N_(d) ν_(d) 1 17.897 0.76 1.80610 40.73 2 6.060 3.11— — 3 10.235 1.79 1.84666 23.78 4 35.572 1.47 — — 5 −11.491 0.60 1.7130053.93 6 −975.094 13.53~5.75~1.15 — — 7 7.081 2.37 1.63246 63.80 8−24.413 0.76 — — 9 9.621 0.60 1.94595 17.98 10 5.884 2.57 — — 11 −48.5241.23 1.51742 52.15 12 −9.264 8.19~12.30~19.23 — — 13 22.153 0.80 1.5247056.24 14 11.862 0.56 — — 15 ∞ 0.64 1.54892 69.76 16 ∞ 0.64 — — 17 ∞ 0.641.51680 64.20 18 ∞ — — — aspherical coefficients 1^(st) surface 2^(nd)surface 7^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A= 9.08795E−04 A = 7.05999E−04 A = −3.29615E−04 B = −5.66115E−05 B =−5.62207E−05 B = −8.69046E−07 C = 1.79363E−06 C = −4.84236E−08 C =−1.90336E−08 D = −2.64987E−08 D = 6.52311E−08 D = −3.22161E−09 E =1.55558E−10 E = −1.39692E−09 8^(th) surface 13^(th) surface 14^(th)surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00 A = 3.69730E−04A = −7.92748E−03 A = −9.80709E−03 B = −9.71883E−07 B = 6.45709E−04 B =7.96636E−04 C = −5.82142E−08 C = −2.23222E−05 C = −2.87699E−05 D =6.79738E−08 D = 2.84988E−07 E = 3.12782E−09

EMBODIMENT 19

A numerical example for a 19^(th) embodiment of a zoom lens of theinvention will be shown in Table 20. In addition, FIG. 37 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 38is a diagram showing aberrations thereof.

TABLE 20 f = 7.21~12.17~20.56 F = 1.96~2.64~3.77 2ω = 66.09~41.08~24.97Surface number R D N_(d) ν_(d) 1 19.074 1.07 1.81474 37.03 2 7.196 3.33— — 3 10.800 1.41 1.90680 21.20 4 25.164 1.44 — — 5 −10.203 0.60 1.7291654.66 6 −135.833 11.75~5.24~1.15 — — 7 6.502 2.59 1.63246 63.80 8−19.202 0.10 — — 9 9.505 0.63 1.92286 20.88 10 5.644 2.89 — — 11 −21.8631.26 1.48749 70.45 12 −7.726 7.65~8.88~12.56 — — 13 −11.251 0.86 1.5247056.24 14 −20.216 0.80~3.67~6.50 — — 15 ∞ 0.64 1.54892 69.76 16 ∞ 0.64 —— 17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients 1^(st)surface 2^(nd) surface 7^(th) surface K = 0.00000E+00 K = 0.00000E+00 K= 0.00000E+00 A = 8.59718E−04 A = 8.46466E−04 A = −4.40865E−04 B =−3.11014E−05 B = −2.84513E−05 B = −2.10515E−06 C = 8.29049E−07 C =1.03543E−07 C = −5.98113E−09 D = −1.09284E−08 D = 2.12528E−08 D =8.78276E−11 E = 6.55720E−11 E = −3.12894E−10 8^(th) surface 13^(th)surface 14^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00A = 5.53958E−04 A = −1.80421E−03 A = −1.88435E−03 B = −4.43099E−06 B =−1.84005E−04 B = −1.08716E−04 C = 1.66778E−07 C = 2.14189E−05 C =1.36062E−05 D = −6.75424E−07 D = −4.81727E−07 E = −1.04548E−08

EMBODIMENT 20

A numerical example for a 20^(th) embodiment of a zoom lens of theinvention will be shown in Table 21. In addition, FIG. 39 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 40is a diagram showing aberrations thereof.

TABLE 21 f = 6.24~10.53~17.77 F = 1.96~2.65~3.80 2ω = 73.81~47.09~28.97Surface number R D N_(d) ν_(d) 1 15.937 0.72 1.82080 42.71 2 5.803 3.40— — 3 11.046 1.60 1.84666 23.78 4 50.714 1.19 — — 5 −10.906 0.60 1.7291654.66 6 217.040 10.82~4.83~1.15 — — 7 6.498 2.29 1.69400 56.30 8 −19.1460.10 — — 9 9.474 0.70 1.94595 17.98 10 5.530 2.59 — — 11 −17.031 1.151.48749 70.45 12 −7.278 6.48~7.63~10.44 — — 13 −33.208 1.20 1.5247056.24 14 96.110 0.76~3.33~6.50 — — 15 ∞ 0.64 1.54892 69.76 16 ∞ 0.64 — —17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients 1^(st)surface 2^(nd) surface 7^(th) surface K = 0.00000E+00 K = 0.00000E+00 K= 0.00000E+00 A = 6.04773E−04 A = 2.82447E−04 A = −4.84216E−04 B =−3.93535E−05 B = −3.82997E−05 B = −3.64447E−06 C = 1.50574E−06 C =−1.81821E−07 C = 1.18953E−07 D = −2.68733E−08 D = 6.33095E−08 D =−7.50550E−10 E = 1.91711E−10 E = −1.66775E−09 8^(th) surface 13^(th)surface 14^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00A = 5.48392E−04 A = −3.60325E−03 A = −3.61113E−03 B = −7.15368E−06 B =−1.50520E−04 B = −5.28512E−05 C = 4.10325E−07 C = 1.46674E−05 C =9.98329E−06 D = −4.58990E−09 D = −1.54888E−07 D = −4.42543E−07 E =−4.61722E−08

EMBODIMENT 21

A numerical example for a 21^(st) embodiment of a zoom lens of theinvention will be shown in Table 22. In addition, FIG. 41 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 42is a diagram showing aberrations thereof.

TABLE 22 f = 6.78~11.45~19.33 F = 1.96~2.59~3.71 2ω = 69.24~43.59~26.79Surface number R D N_(d) ν_(d) 1 21.346 1.20 1.80139 45.45 2 6.706 2.92— — 3 9.220 1.65 1.80518 25.46 4 22.664 1.53 — — 5 −10.558 0.60 1.7130053.93 6 −239.406 11.77~5.18~1.15 — — 7 6.127 2.64 1.59240 68.30 8−17.843 0.10 — — 9 9.432 0.60 1.84666 23.78 10 5.430 2.72 — — 11 −21.8771.30 1.49700 81.61 12 −7.458 7.74~10.13~14.95 — — 13 −18.253 0.801.60717 29.00 14 −46.532 0.80~2.44~4.14 — — 15 ∞ 0.64 1.54892 69.76 16 ∞0.64 — — 17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients1^(st) surface 2^(nd) surface 7^(th) surface K = 0.00000E+00 K =0.00000E+00 K = 0.00000E+00 A = 1.20467E−03 A = 1.34100E−03 A =−5.13225E−04 B = −3.77105E−05 B = −3.05456E−05 B = −2.99283E−06 C =8.31782E−07 C = −1.62280E−07 C = 7.30923E−08 D = −9.81491E−09 D =2.33953E−08 D = −4.31509E−09 E = 5.46771E−11 E = −2.23641E−10 8^(th)surface 13^(th) surface 14^(th) surface K = 0.00000E+00 K = 0.00000E+00K = 0.00000E+00 A = 6.53620E−04 A = −2.03194E−03 A = −2.55278E−03 B =−3.25133E−06 B = −2.81251E−04 B = −1.49009E−04 C = 1.51177E−07 C =2.90448E−05 C = 1.67952E−05 D = −8.59119E−07 D = −4.93972E−07 E =−3.68943E−09

EMBODIMENT 22

A numerical example for a 22^(nd) embodiment of a zoom lens of theinvention will be shown in Table 23. In addition, FIG. 43 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 44is a diagram showing aberrations thereof.

TABLE 23 f = 7.39~12.48~21.06 F = 1.96~2.62~3.73 2ω = 65.13~39.63~23.90Surface number R D N_(d) ν_(d) 1 15.869 0.72 1.81474 37.03 2 6.667 3.18— — 3 10.994 1.78 1.84666 23.78 4 35.151 1.59 — — 5 −11.860 0.60 1.7291654.66 6 −263.629 13.87~5.97~1.15 — — 7 6.954 2.52 1.56907 71.30 8−18.119 0.71 — — 9 11.113 0.66 1.92286 20.88 10 6.443 2.65 — — 11−44.977 1.30 1.51823 58.96 12 −8.568 7.70~8.76~10.79 — — 13 −9.935 0.601.48749 70.45 14 −30.569 0.74~3.31~7.00 — — 15 ∞ 0.64 1.54892 69.76 16 ∞0.64 — — 17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients1^(st) surface 2^(nd) surface K = 0.00000E+00 K = 0.00000E+00 A =3.78966E−04 A = 2.07611E−04 B = −1.93884E−05 B = −2.21333E−05 C =5.84045E−07 C = 2.23132E−07 D = −7.82448E−09 D = 7.02082E−09 E =4.56451E−11 E = −1.59634E−10 7^(th) surface 8^(th) surface K =0.00000E+00 K = 0.00000E+00 A = −3.72392E−04 A = 4.88425E−04 B =−1.78195E−06 B = −3.79645E−06 C = −1.22161E−08 C = 9.63737E−08 D =−1.43045E−11

EMBODIMENT 23

A numerical example for a 23^(rd) embodiment of a zoom lens of theinvention will be shown in Table 24. In addition, FIG. 45 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 46is a diagram showing aberrations thereof.

TABLE 24 f = 6.80~11.48~19.37 F = 1.96~2.57~3.55 2ω = 69.20~42.83~26.03Surface number R D N_(d) ν_(d) 1 16.220 0.72 1.81474 37.03 2 6.214 3.26— — 3 10.545 1.62 1.84666 23.78 4 26.619 1.70 — — 5 −10.396 0.60 1.5924068.30 6 −114.194 13.86~6.06~1.15 — — 7 6.997 2.58 1.56907 71.30 8−15.232 1.00 — — 9 15.438 0.60 1.84666 23.78 10 6.905 2.10 — — 11−44.097 1.55 1.48749 70.45 12 −7.771 7.86~8.79~11.95 — — 13 −7.917 0.801.52470 56.24 14 −12.408 0.68~3.62~6.50 — — 15 ∞ 0.64 1.54892 69.76 16 ∞0.64 — — 17 ∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients1^(st) surface 2^(nd) surface 7^(th) surface K = 0.00000E+00 K =0.00000E+00 K = 0.00000E+00 A = 7.42964E−04 A = 5.52326E−04 A =−4.08870E−04 B = −4.04783E−05 B = −3.65061E−05 B = 3.39731E−08 C =1.26829E−06 C = −2.28480E−07 C = −1.70352E−08 D = −1.90846E−08 D =4.86906E−08 D = 2.20197E−10 E = 1.16409E−10 E = −1.01645E−09 8^(th)surface 14^(th) surface K = 0.00000E+00 K = 0.00000E+00 A = 5.61347E−04A = −1.90958E−04 B = −2.78540E−06 B = 3.43699E−05 C = 9.62261E−08 C =−5.10868E−06 D = 3.20611E−07 E = −7.42682E−09

EMBODIMENT 24

A numerical example for a 24^(th) embodiment of a zoom lens of theinvention will be shown in Table 25. In addition, FIG. 47 is a diagramshowing the configuration of lens elements of the zoom lens, and FIG. 48is a diagram showing aberrations thereof.

TABLE 25 f = 6.34~10.70~18.07 F = 2.20~2.96~4.23 2ω = 72.98~46.35~28.44Surface number R D N_(d) ν_(d) 1 14.634 0.72 1.82080 42.71 2 5.433 2.80— — 3 9.861 1.73 1.75211 25.05 4 93.805 1.01 — — 5 −10.690 0.60 1.7291654.66 6 111.312 10.02~4.53~1.15 — — 7 6.352 1.92 1.69400 56.30 8 −15.4910.10 — — 9 11.532 0.75 1.94595 17.98 10 6.104 1.94 — — 11 −10.969 1.051.51823 58.96 12 −6.223 6.58~7.54~9.54 — — 13 −15.663 1.20 1.52470 56.2414 −368.432 0.56~3.05~6.50 — — 15 ∞ 0.64 1.54892 69.76 16 ∞ 0.64 — — 17∞ 0.64 1.51680 64.20 18 ∞ — — — aspherical coefficients 1^(st) surface2^(nd) surface 7^(th) surface K = 0.00000E+00 K = 0.00000E+00 K =0.00000E+00 A = 4.83418E−04 A = 9.08249E−05 A = −5.88057E−04 B =−3.76316E−05 B = −4.08304E−05 B = 2.34603E−07 C = 1.80650E−06 C =−1.54844E−07 C = −2.12783E−07 D = −3.87164E−08 D = 9.31813E−08 D =1.84163E−08 E = 3.27232E−10 E = −3.03998E−09 8^(th) surface 13^(th)surface 14^(th) surface K = 0.00000E+00 K = 0.00000E+00 K = 0.00000E+00A = 7.26207E−04 A = −4.43529E−03 A = −4.41608E−03 B = −5.68176E−06 B =−2.56504E−04 B = 1.47767E−05 C = 2.14998E−07 C = 3.59018E−05 C =3.81834E−06 D = 1.28436E−08 D = −2.61866E−06 D = −2.85526E−07 E =2.56084E−08

Next, with respect to Embodiments 17 to 24, values corresponding to theconditional expressions (16) to (30) will altogether be shown in Table26.

TABLE 26 Embod- Embodi- Embod- iment Embodiment ment iment 17 18 19 20Conditional expression (16) −0.56 −0.58 −0.63 −0.63 Conditionalexpression (17) 5.77 6.10 5.32 5.69 Conditional expression (18) −0.14−0.13 −0.14 −0.13 Conditional expression (19) 0.40 0.40 0.36 0.38Conditional expression (20) 21.70 23.55 24.65 24.90 Conditionalexpression (21) 1.85 1.85 1.91 1.85 Conditional expression (22) 1.091.09 1.00 1.08 Conditional expression (23) 0.58 0.59 0.67 0.53Conditional expression (24) 0.78 0.74 0.90 0.86 Conditional expression(25) −0.42 −0.38 −0.44 −0.41 Conditional expression (26) 46.87 39.9946.24 45.39 Conditional expression (27) −0.38 −0.37 −0.36 −0.36Conditional expression (28) 1.03 0.93 1.11 0.96 Conditional expression(29) −0.81 −0.76 −0.84 −0.89 Conditional expression (30) −0.57 0.30−0.64 −0.19 Embod- Embodi- Embod- iment Embodiment ment iment 21 22 2324 Conditional expression (16) −0.63 −0.54 −0.56 −0.64 Conditionalexpression (17) 5.66 5.52 6.02 5.20 Conditional expression (18) −0.14−0.43 −0.15 −0.20 Conditional expression (19) 0.37 0.40 0.34 0.44Conditional expression (20) 24.24 22.06 28.88 23.64 Conditionalexpression (21) 1.81 1.85 1.85 1.75 Conditional expression (22) 1.011.11 1.09 1.17 Conditional expression (23) 0.73 0.61 0.59 0.55Conditional expression (24) 0.81 0.81 0.77 0.94 Conditional expression(25) −0.42 −0.41 −0.45 −0.43 Conditional expression (26) 51.17 44.2447.09 39.64 Conditional expression (27) −0.30 −0.38 −0.32 −0.34Conditional expression (28) 1.11 1.06 0.97 1.00 Conditional expression(29) −0.82 −0.81 −0.90 −1.02 Conditional expression (30) −0.37 −0.74−0.86 −0.40

As is obvious from Table 26, the values for each embodiment fromEmbodiments 17 to 24 satisfy the conditional expressions (16) to (30),and as is obvious from the aberration diagrams of each embodiment, theindividual aberrations are corrected properly.

According to these embodiments, by configuring the zoom lens opticalsystem having a zoom ratio of the order of 3× as three groups of lenselements by the use of seven or eight lens elements and givingsequentially from the object side negative, positive and negative powersto each lens elements group, the overall length of the zoom lens in thedirection of the optical axis thereof can be reduced when used, and bydisposing symmetrically not only the configuration of lens elementsgroups but also positive and negative power arrangement in the directionfrom an object side to an image side and schematic configuration of eachof the individual lens elements which make up the whole system, theoccurrence of off-axis aberrations such as distortion and astigmatism isbasically reduced, whereby the degree of freedom of correctionenvironment of the individual aberrations can be improved overall, andwith an ƒ number of the order of 2, a zoom lens which is fast butcompact and which maintains high performance can be realized, therebymaking it possible to provide a compact zoom lens which makes itdifficult for blurs due to the movement of a camera and a subject to beproduced and a camera with the zoom lens.

1. A zoom lens comprising, sequentially from an object side thereof, afirst lens elements group having a negative refraction power as a whole,a second lens elements group having a positive refraction power as awhole, and a third lens element group having a negative refraction poweras a whole, wherein the first lens elements group is made up bydisposing three lens elements which include a first lens element whichis a negative lens, a second lens element which is a positive lens, anda third lens element which is a negative lens, wherein the second lenselements group is made up by disposing four lens elements which includea fourth lens element which is a positive lens, a fifth lens elementwhich is a positive lens, a sixth lens element which is a negative lens,and a seventh lens element which is a positive lens, and where the thirdlens element group is made up by disposing an eighth lens element whichis a negative lens, wherein a variable power is realized by shiftingpositions of the first lens elements group and the second lens elementsgroup in a direction of an optical axis thereof, or shifting, inaddition to the first lens elements group and the second lens elementsgroup, a position of the third lens element group, wherein aconfiguration of positive/negative powers of the individual lenselements of the whole lens system is made to be a configuration ofnegative, positive, negative, positive, positive, negative, positive,negative which is symmetrical with respect to a boundary between thefourth lens element and the fifth lens element, and wherein adistribution of volumes of powers of the constituent lens elements isalso made to be substantially symmetrical in a similar manner.
 2. Acamera which is adapted to have installed thereon the zoom lensaccording to claim
 1. 3. A zoom lens comprising, sequentially from anobject side thereof, a first lens elements group having a negativerefraction power as a whole, a second lens elements group having apositive refraction power as a whole, and a third lens element grouphaving a negative refraction power as a whole, wherein the first lenselements group is made up by disposing three lens elements which includea first lens element which is a negative lens and which has a meniscusconfiguration that is convex on an object side surface thereof, a secondlens element which is a positive lens and which has a meniscusconfiguration that is convex on an object side surface thereof, and athird lens element which is a negative lens, wherein the second lenselements group is made up by disposing three lens elements which includea fourth lens element which is a positive lens, a fifth lens elementwhich is a negative lens and which has a meniscus configuration that isconvex on an object side surface thereof, and a sixth lens element whichis a positive lens, and wherein the third lens element group is made upby disposing a seventh lens element which is a negative lens, wherein avariable power is realized by shifting positions of the first lenselements group and the second lens elements group in a direction of anoptical axis thereof, or shifting, in addition to the first lenselements group and the second lens elements group, a position of thethird lens element group, wherein a configuration of positive/negativepowers of the individual lens elements of the whole lens system is madeto be a configuration of negative, positive, negative, positive,negative, positive, negative which is symmetrical with respect to thefourth lens element which constitutes a center of the configuration, andwherein a distribution of volumes of powers of the constituent lenselements is also made to be substantially symmetrical in a similarmanner.
 4. A camera which is adapted to have installed thereon the zoomlens according to claim 3.